Pressure-indicator.



R. WOOD.

PRESSURE INDICATOR.

APPLICATION FILED DEG.16, 1912. 1 1 1 7,470, Patented Nov. 17, 1914.

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' Attorneys THE NORRIS PETERS CO PHOTO-LITHO-i WISE-""117"," '8

R. WOOD.

PRESSURE INDICATOR.

APPLICATION rum) DEG.16, 1912.

Patented Nov. 17, 1914 2 $HEETSSHEET 2.

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THE NORRIS PETERS c0. PHOTO-LITHQ, WASHING TON. D. C.

ROBERT WOOD, OF WESTMOUNT, QUEBEC, CANADA.

PRESSURE-INDICATOR.

Specification of Letters Patent.

Patented Nov. 17, 1914.

Application filed December 16, 1912. Serial No. 736,881.

To all whom it may concern:

Be it known that I, ROBERT WOOD, a subject of the King of Great Britain, residing at 4930 WVestern avenue, lVestmount, Province of Quebec, Canada, have invented certain new and useful Improvements in Pressure-Indicators; and I do hereby declare that the following is a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The invention to be hereinafter described relates to fluid pressure indicators.

In order to more clearly disclose the construction, operation, and use of the invention, reference should be had to the accompanying drawings forming part of the pres ent application.

Throughout the several figures of the drawings like reference characters designate the same parts.

In the drawings: Figure l is a side elevation of the invention; Fig. 2 is a plan view of an indicator record; Fig. 3 is a central, vertical, longitudinal, cross section of the invention; and Fig. at is a similar view, enlarged, of the piston valve, its chambers, and ports.

The main objects of the invention are to provide a simple, efficient, economical, and

compact indicator which will be absolutely accurate and erations.

The drum and its actuating connections with the cylinder piston are the same as in the usual standard indicator of this type. The same-is true as regards the connections and arrangements for delivering steam from the cylinders to the indicator. Consequently, such parts and arrangements need not be further described here.

Referring to the drawings in detail, 1 indicates a top section, 2 a middle section, and 3 a lower section of the barrel of an indicator. The middle section is internally screw threaded at its opposite ends to removably receive the top and lower sections which are provided with cooperating screw threaded extensions. The top section is also provided with a laterally extended wall or flange 4 which projects beyond the face of the section 2, and the section 2, for a considerable distance below its top edge is somewhat reduced in diameter, or cut down, for a purpose to be later disclosed. The lower section 3 is centrally bored to form a lower piston positively unvarying in its opchamber 5 for a sliding piston 6 fixed to the lower end of a piston rod 7. The middle sect1on 2 is similarly bored out to a considerably greater diameter, as at 8, to form a central piston chamber for a larger piston 9, also fixed to the piston rod 7. This central piston chamber is in continuation of lower piston chamber 5, when the parts are assembled. The middle section 2 is also provided with a guide bore 10 leading from the chamber 8 and slidably receiving an upper piston 11 also fixed to the piston rod 7. The bore 10 and chamber 5 as well as the pistons 6 and 11, are of exactly the same diameter. A steam chamber 12, of somewhat greater diameter than the bore 10 and concentric therewith, forms a continuation of the bore, while the top section 1 is provided with an annular chamber 13 in continuation of the chamber 12, a tubular boss 14 projecting downwardly from the section 1, concentric with the annular chamber 13, and in position to engage the upper face of piston 11 and thus limit the upward travel of the piston, as will be clear. In the upper part of the wall of chamber 12 and the lower part of the chamber 5 are provided steam inlet ports 15 and 16, respectively. These ports communicate with each other by way of a tubular steam passage 17 the greater part of which is inclosed by a hand grip or handle 18. Also, a diagonal feed passage 19 leads from a point beneath the piston 6 to the port 16, so that steam will be delivered direct from the engine cylinder and connections through passage 19 and into port 16. From the port 16 the steam passes simultaneously into the passage 17 and into a lateral passage 20 in the lower part of piston 6. This lateral passage communicates with the lower end of a vertical passage extending upwardly through the piston rod to the lower face of the piston 9. From this vertical passage, branch out a plurality of lateral steam delivery passages. The result of this arrangement is that steam of the engine cylinder,

under very high compression, rushes through the diagonal passage 19 and thence into the port 16. From port 16 it rushes through the lateral passage 20 and communicating passages to the under side of piston 9 and, at the same time, through passage 17 and the port 15 into chamber 12 and against the upper face of the piston 11. At the instant of entry from the engine cylinder, however, the steam rushes against the lower face of the piston 6 which has the same area as the upper face of piston 11.

The entry of steam to the faces ofthe three pistons 6, 9, and 11 is, to all practical intents, simultaneous, as will be evident. The net result is that the pressures on 6 and 11 are balanced, each by the other, leaving the pressureon 9 free todrive the pistons from the position of Fig. 3 to that of Fig. f. This movement is accomplished in a very small fraction of a second. The instant that the piston is thus shifted, the passage 20 will be shut off from port 16, thereby preventing further admission of steam beneath piston 9. The result of this is that the piston will be held suspended in the position of Fig. equal pressure on each of pistons 6 and 11. Furthermore, normally, it would remain in this suspended position as long as there was any pressure coming from the engine cylinder, regardless of the steady decrease in the cylinder pressure. But, to avoid this dii'liculty and destroy this condition of equilibrium, an air port 21 is provided leading to the interior of the chamber 8, above the piston 9. Admission of atmospheric pressure, in this manner, will permit the pistons to gravitate gradually downward in exact accordance with the decrease of pressure in the engine cylinder. As long as the pressure is stationary until the feed to the cylinder is automatically cut off, during each piston stroke) the pistons will remain suspended as in Fig. of course, but as soon as the pressure begins to decrease, clownward movement will begin, as will be ob- .vious.

The piston rod is made to usual recording pencil, stylus, or other like device in well known manner. Such devices are carried by a sleeve 22 rotatably mounted on the reduced upper end of the middle section 2 and held against removal by the flange 1, as will be clear. This sleeve is provided with an arcuate slot 23 and an entrance notch leading therefrom to permit assemblage of the parts and free rotary sliding movement of the sleeve relatively to the tube containing the passage 17, as will be readily seen on reference to Figs. 1 and 3.

The opening 21 may be made more or less restricted, to produce a slight cushioning effect of the piston 9 in its upward travel.

The atmospheric pressure used in returning the pistons has none of the numerous disadvantages of springs or other mechanical means. It is absolutely regular and does not have to be changed to accord with the different pressures of the cylinders under test. Its action is natural and its operation is uniform and invariable at all stages.

In Fig. 2, the line C-B indicates the operate the a by the balanced or period of sustained high pressure before the steam is shut off, and the line Cl) indicates the period from the time of shutting off until the end of the strokeof the cylinder piston. The line (3-D, in this case, shows a gradual, regular, and uniform decrease of pressure.

Although the indicator has been described as applied to steam engine cylinders, it is obvious that it may be equally applied to gas engines and, in fact, in practically any case where it is desired to determine the expansive action of a fluid pressure medium.

It is thought that the construction, operation, and use of the invention will be clear from the preceding detailed description.

Changes may be made in the construction, arrangement, and disposition of the several parts of the invention without in any way departin from the field and scope of the same, and it is meant to include all such within this application wherein only a preferred form has been disclosed.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a device of the character described, a barrel adapted to be connected to a source of fluid pressure, pistons slidably mounted therein, means for suspending said pistons under motive fluid pressure simultaneously introduced against opposing surfaces thereof in equilibrium within said barrel, and means for destroying the equilibrium of said pistons.

2. In a device of the character described, a barrel adapted to be connected to a source of fluid pressure, a piston rod slidably mounted therein, upper and lower pistons of equal surface secured to said rod, a pistion of greater area secured to said piston rod between the aforesaid pistons, ports and passages for admitting fluid pressure simultaneously to the lower faces of the lower and central pistons and to the upper face of the upper piston, and a port for subsequently admitting atmospheric pressure to the upper face of the central piston.

3. In a device of the character described, a barrel adapted to be connected to a source of fluid pressure, gravity returned pistons slidably mounted therein, and -means for moving said pistons under motive fluid pressure to a suspended position of equilibrium with the actuating motive fluid againstopposite faces thereof and so temporarily maintaining them.

4C. In a device of the character described, the combination with an indicating element, of piston mechanism for operating the same, and springless means for actuating the piston mechanism, including means for directing the actuating motive fluid against opposing surfaces of the piston mechanism, to

move the same in one direction, said piston mechanism being returned by gravity when relieved of motive fluid pressure.

5. In a device of the character set forth, the combination with an indicating element, of a piston member having opposing surfaces, and means for simultaneously directing motive fluid against the opposing surfaces and causing the movement of the piston member by the overhalance of pressure on one side of the same, to effect the operation of the indicating element.

6. In a device of the character described, the combination with piston mechanism, including oppositely disposed piston surfaces, of means for admitting motive fluid against both surfaces simultaneously, and means for overbalancing the pressure against one of the surfaces to cause the mechanism to move against the resistance of the piston surface so overbalanced.

7. In a device of the character described, the combination with piston mechanism, including oppositely disposed piston surfaces, of means for admitting motive fluid against both surfaces simultaneously, a third piston surface opposite to one of the first-mentioned surfaces, and means for admitting motive fluid against the various surfaces to cause two of said surfaces to overbalance the third.

8. In a device of the character described, the combination with piston mechanism, including oppositely disposed piston surfaces, of means for admitting motive fluid against both surfaces simultaneously, a third piston surface opposite to one of the first-mentioned surfaces, means for admitting motive fluid against the various surfaces to cause two of said surfaces to overbalance the third, and means for cutting off the supply of motive fluid against the third piston surface when the piston mechanism is moved a predetermined distance.

In a device of the character described, the combination with piston mechanism having two opposing areas of relatively small extent and a third area greater than that of either of the smaller areas and opposing one of said smaller areas, of means for simultaneously admitting motive fluid against all the said areas, and means for automatically cutting off the motive fluid against one of said areas when the piston mechanism is moved a predetermined distance.

10. In a device of the character described, the combination With a casing, of a handle connected to the same, piston mechanism in the casing, and means for directing motive fluid to the piston mechanism including a passageway that extends through the handle and opening on opposite sides of the piston mechanism.

11. In a device of the character described, the combination with a casing, of a handle located alongside the same and connected at both ends thereto, piston mechanism operating in the casing, and means for directing motive fluid in the casing to the piston mechanism, including a passageway that extends longitudinally through the handle and its connections with the casing.

In witness whereof I have hereunto set my hand in the presence of two Witnesses.

ROBERT WOOD.

Witnesses:

L. A. GAUVIN, E. J. GAUVIN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner 0! Patents, Washington, D. C. 

